As an inductance element used in various electronic devices, an inductance element is widely known which has a structure in which a conductive wire is wound around a drum-shaped core and both ends of the conductive wire are connected to terminal electrodes formed on the core.
For example, Japanese Unexamined Patent Application Publication No. 2010-171054 discloses an existing inductance element having such a structure. FIG. 9 shows an inductance element 800 disclosed in Japanese Unexamined Patent Application Publication No. 2010-171054.
The inductance element 800 includes a drum-shaped core 101. The core 101 has a structure in which an upper flange portion 102 and a lower flange portion 103 are formed on both ends of a winding-core portion (not shown). In FIG. 9, for convenience of explanation, the inductance element 800 is turned upside down, namely, is shown such that the upper flange portion 102 is located on the lower side and the lower flange portion 103 is located on the upper side.
The lower flange portion 103 has an inner surface (not shown) on the winding-core portion side, a bottom surface 103a, a pair of side surfaces 103b, and a pair of end surfaces 103c. Each side surface 103b is formed in a shape in which a plurality of surfaces are connected in series.
In addition, a conductive wire 104 is wound around the winding-core portion of the core 101 and covered with an insulating coating.
Further, a pair of terminal electrodes 105 is formed on the bottom surface 103a of the lower flange portion 103 of the core 101. The insulating coating is removed from both end portions 104a of the conductive wire 104, and both end portions 104a are connected to the respective terminal electrodes 105, through the side surface 103b and the bottom surface 103a of the lower flange portion 103.
In the inductance element 800, a pair of grooves 103d is formed in the bottom surface 103a of the lower flange portion 103, and both end portions 104a of the conductive wire 104 are accommodated in the grooves 103d. In addition, the terminal electrodes 105 are formed by burying solder in recesses (not shown) provided in the bottom surface 103a of the lower flange portion 103. However, the grooves 103b are not necessarily needed. In addition, the terminal electrodes 105 are generally formed by burning a silver paste onto the bottom surface 103a of the lower flange portion 103, rather than by burying the solder in the recesses.
However, when being mounted by means of reflow soldering using cream solder or the like, the existing inductance element 800 described above can appropriately be mounted on a land electrode having a specific width, but cannot appropriately be mounted on a land electrode having a width other than the specific width.
In other words, besides the inductor element, for an electronic component, a recommended land electrode dimension is often specified by its manufacturer or distributor (hereinafter, referred to “manufacturer etc.”). For example, an A company, which is a manufacturer etc., recommends a pair of land electrodes (hereinafter, referred to as “narrow land electrodes 201”) each having a width of about 1.0 mm and a length of about 0.9 mm and arranged so as to face each other at an interval of about 0.8 mm as shown in FIG. 10A, and manufactures and sells inductance elements including terminal electrodes corresponding to these land electrodes. Meanwhile, a B company, which is another manufacturer etc., recommends a pair of land electrodes (hereinafter, referred to as “wide land electrodes 202”) each having a width of about 1.6 mm and a length of about 0.65 mm and arranged so as to face each other at an interval of about 0.7 mm as shown in FIG. 10B, and manufactures and sells inductance elements including terminal electrodes corresponding to these land electrodes.
It is noted that mounting of an inductance element is conducted by applying cream solder or the like to the surfaces of the narrow land electrodes 201 or wide land electrodes 202 formed on a substrate, disposing the inductance element thereon, putting the substrate into a tunnel furnace or the like, heating the substrate in the tunnel furnace or the like, taking out the substrate from the tunnel furnace or the like, and cooling the substrate.
Since each terminal electrode 105 is formed so as to have a width of about 1.0 mm, the inductance element 800 can appropriately be mounted on the narrow land electrodes 201 as shown in FIG. 11A (In FIG. 11A, portions of the narrow land electrodes 201 which are hidden by the inductance element 800 are shown by dotted lines, and the terminal electrodes 105, which cannot be seen since the terminal electrodes 105 are formed on the bottom surface of the inductance element 800, are shown by dotted lines with hatching. The same applies to FIGS. 11B, 13A, and 13B.).
However, when the inductance element 800 is mounted on the wide land electrodes 202, the inductance element 800 may rotate on the wide land electrodes 202 as shown in FIG. 11B. This is because when heating is conducted and cream solder is melted, the position of the inductance element 800 is not stabilized and the inductance element 800 moves.
In order to appropriately mount the inductance element on the wide land electrodes 202, the terminal electrodes have to be formed so as to have large widths. FIG. 12 shows another existing inductance element 900 in which the widths of the terminal electrodes 105 of the inductance element 800 are increased.
In the inductance element 900, each terminal electrode 115 is formed so as to have a width of about 1.6 mm. The other configuration of the inductance element 900 is the same as that of the inductance element 800 described above.
As a result, the inductance element 900 can appropriately be mounted on the wide land electrodes 202 as shown in FIG. 13A.
However, when the inductance element 900 is mounted on the narrow land electrodes 201, the inductance element 900 may shift to one side of the narrow land electrodes 201 as shown in FIG. 13B. This is because when heating is conducted and cream solder is melted, the position of the inductance element 900 is not stabilized and the inductance element 900 moves.
As described above, when the existing inductance element 800 or 900 is mounted by means of reflow soldering using cream solder or the like, the inductance element can appropriately be mounted on land electrodes each having a specific width, but cannot appropriately be mounted on land electrodes each having a width other than the specific width. In other words, if the dimensions of the land electrodes recommended by the A company and the B company are different from each other, only the inductance element of the A company can be mounted on the land electrodes recommended by the A company, only the inductance element of the B company can be mounted on the land electrodes recommended by the B company, and each inductance element is not compatible with the land electrodes of the other company.
It is noted that in the existing inductance element 900 in which each terminal electrode 115 has an increased width, it is difficult to find breakage of the conductive wire 104. In other words, each end portion 104a of the conductive wire 104 is connected to the terminal electrode 115 formed on the bottom surface 103a of the lower flange portion 103, through the side surface 103b of the lower flange portion 103, and the conductive wire 104 is likely to be broken near the side formed by the side surface 103b and the bottom surface 103a of the lower flange portion 103. However, when each terminal electrode 115 having an increased width is present on the bottom surface 103a of the lower flange portion 103 and near the side formed by the side surface 103b and the bottom surface 103a, breakage of the conductive wire 104 in this portion is easily overlooked during inspection with naked eyes. In other words, the conductive wire 104, from which the insulating coating is removed, and each terminal electrode 115 have metal colors, and thus it may be erroneously determined that the conductive wire 104 is not broken, even if the conductive wire 104 is broken.